Sharing some technical knowledge is great!

I am a newbie in this kind of stuff but lately I’ve been hearing a lot about how good NodeJS is. Considering how much I love working with jQuery and Javascript in general, I can’t help but wonder how to decide when to use NodeJS. The web application I have in mind is something like bit.ly – takes some content, archives it. From all the homework I have been doing in the last few days, I obtained the following information. NodeJS

is a command-line tool that can be run as a regular web server and lets one run Javascript programs

utilizes the great V8 JS engine

is very good when you need to do several things at the same time

is event-based so all the wonderful Ajax like stuff can be done on the server side

Considering that NodeJS can be run almost out-of-the-box on Amazon’s EC2 instances, I am trying to understand what type of problems require NodeJS as opposed to any of the mighty kings out there like php, python and ruby. I understand that it really depends on the expertise one has on a language but my question falls more into the general category of: When to use a particular framework and what type of problems is it particularly suited for?